Hail, Calhoun
- When
- May 20, 12:45 AM CST
- Where
- Calhoun County, Rockwell City
- Measured
- 0.75 in hail
- Property damage
- $1,000
- Crop damage
- $500
- Reported by
- LAW ENFORCEMENT
- Coordinates
- 42.400, -94.630
Hail in Iowa, May 20, 1999
A strong southerly flow of air brought moisture north into Iowa and produced a round of warm air advection thunderstorms to the northwest half of the state. The nocturnal thunderstorms developed well east of an approaching cold front.
Where it happened
Every event with a place to put it. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- $1,000
- Crop damage
- $500
- Events
- 1
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
What happened
The episode as NWS DMX wrote it up.
A strong southerly flow of air brought moisture north into Iowa and produced a round of warm air advection thunderstorms to the northwest half of the state. The nocturnal thunderstorms developed well east of an approaching cold front. Even though there was no actual surface warm front in place, the thunderstorms formed at the nose of the deeper moisture in the low level jet stream. There were numerous reports of pea to marble size hail over west central into north central Iowa, but most of the hail remained below severe levels. One of the storms became stronger over Calhoun County. Hail reportedly covered the ground in the city. A few of the hail stones were up to three quarters of an inch in diameter.
The radar
The Des Moines radar (KDMX), 106 km away, was scanning. The volume nearest the first event began at 06:44 UTC.
Event by event
1 hail. Local standard time, as filed.
What these are
- Hail
- Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Flash Flooding and Damaging Winds in Nebraska, May 20, 1999
- Tornado and Hail in Kansas, May 20 to 22, 1999
- Hail and Damaging Winds in Oklahoma, May 20 to 21, 1999
- Tornadoes and Hail in Texas, May 20, 1999
- Tornado in Montana, May 20, 1999
- Hail and Damaging Winds in Kansas, May 20, 1999
- Hail in Florida, May 20, 1999
- Flash Flooding and Hail in Kansas, May 20, 1999
- Tornadoes and Hail in Texas, May 20, 1999
- Hail in Oklahoma, May 20, 1999
- Hail in Kansas, May 20, 1999
- Flash Flooding in Kansas, May 20, 1999
More
Every storm in Iowa in 1999Every state in 1999This day in weather historyWarnings in Iowa, May 1999
Sources
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5693478.